and many more benefits!

Find us on Facebook

GMAT Club Timer Informer

Hi GMATClubber!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

A circular rim 28 inches in diameter rotates the same number [#permalink]
09 Dec 2007, 10:21

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A circular rim 28 inches in diameter rotates the same number of inches
per second as a circular rim 35 inches in diameter. If the smaller
rim makes y revolutions per second, hom many revolution per minute
does the larger rim make in terms of y
------------------------------------------------------------------------

The ratio of two quantities is 3 to 4. If each of the quantities is
increased by 5, what is the ratio of these two new quantities

First problem:
First let's find the number of inches the small and large rim rotate in one revolution - it is circumference length or:
smaller rim: 2piR=28pi (which is around 84 but we won't need this number).
larger rim: 2piR=35pi
Let x be number of revolutions per minte the larger rim makes => x/60 - number of revolutions per second.
If a smaller rim makes y revolutions per second then it rotates 28pi*y number of inches per second which equals number of inches per second of larger rim or 35pi*x/60. Solve it for x:
28piy=36pix/60 => 36x=1680y => x=140/3*y
That's what I got... strange answer. I wonder if it is in the answer choices?

Second problem:
To my mind it's impossible to tell what will be the ratio of new quantities. If we take different numbers with the given ratio and check them the new ratios will be different:
1) If we take 3 and 4. 3+5=8, 4+5=9, so the ratio is 8/9.
2) If we take 6 and 8. 6+5=11, 8+5=13, so the ratio is 11/13
We get two different ratios, so we can't say for sure what will be the answer.

24 permutations means that on the ones we will have 6x1's, 6x2's,6x3's,6x4's
6+12+18+24=60
same on the tens, hundredths and thousands
so 60+600+6000+60000=66660
=================================
where did you get these questions from

A circular rim 28 inches in diameter rotates the same number of inches per second as a circular rim 35 inches in diameter. If the smallerrim makes y revolutions per second, hom many revolution per minutedoes the larger rim make in terms of y------------------------------------------------------------------------

24 permutations means that on the ones we will have 6x1's, 6x2's,6x3's,6x4's6+12+18+24=60same on the tens, hundredths and thousandsso 60+600+6000+60000=66660=================================where did you get these questions from